A lump in the skin with a white substance that smells bad when pressed may be a sebaceous cyst, which can be treated with surgical excision under local anesthesia. Sebaceous cysts are very common benign skin diseases, mainly due to sebaceous gland excretory duct obstruction, the sebaceous gland cystic epithelium by the gradual increase in the contents of the swelling of the formation of retention cysts, may appear as a symptom of the skin with lumps and press out the white material is very smelly. Sebaceous cysts generally can not be self-healing, and oral or topical drug treatment has no obvious effect, if you want to cure the most common method is surgical resection under local anesthesia. If the cyst is infected, antibiotics should be used first, and then surgical excision should be performed after the infection is controlled. If there is a lump in the skin, press out the white material is very smelly, you need to go to the hospital in time to clarify the cause of the disease, and standardized treatment by a professional doctor, so as not to delay the condition.